1. Field of the Invention
The present invention relates to an apparatus suitable for searching an underwater object, and particularly to a fish finder, which transmits ultrasonics from a transducer attached to the bottom of a ship into a body of water, receives reflected ultrasonics from fish schools or the like, converts the received ultrasonics to an electric signal and further to digital data, and displays on a display device, based on the obtained data, an image representative of any schools of fish present and, if present, its concentration and size.
2. Description of the Related Art
Fish finders visually display an image representative of the concentration and size of any school of fish present in an operation area of a fishing boat, and are widely used in such fishing boats and other watercraft. However, conventional fish finders have a fault in that they require a significant time to detect a school of fish. Specifically, for accurate detection and display of the location and size of a school of fish, a transducer with narrow directivity must be used. However, when such a transducer with narrow directivity is used, only a narrow area can be scanned. Therefore, in order to locate fish schools, the ship must move around its operation zone to conduct a close search. This contributes to increased operation hours and, as a consequence, increases labor and fuel costs.